In the field of helicopters, engineers are constantly seeking to improve the ability of a rotor blade to flap during flight. While several systems may allow a rotor blade to bend upwards 4 degrees from the flapping axis and downwards 4 degrees form the flapping axis, exceeding a +/−4 degree flapping range poses great challenges.
Previous systems have provided means for enhancing the flapping range of pass-through rotor blades that are stacked on top of one another. However, advantages may be gained by configuring the rotor hub assembly in an in-plane configuration (e.g., wherein all yokes lie in a common plane). For example, an in-plane configuration comprising yokes that terminate radially outward of the mast may be more time and cost efficient to manufacture in comparison to a stacked, pass-through configuration (e.g., using racetrack-style yoke), and an in-plane configuration may exert less load on the hub and mast compared to a pass-through configuration.
In-plane configurations may comprise a yoke that includes a lug that is secured to the hub by way of a bolted joint. Thus, when designing an in-plane rotor configuration, attention must be given to the fact that flapping of the rotor blade (and hence flapping of the associated yoke) may exert shear on the bolted joint. Therefore, needed is an in-plane rotor assembly that facilitates rotor blade flapping while reducing the amount of shear exerted on the bolted joint.